1. Field of the Invention
The invention relates to a set comprising a medical implantable lead being adapted to be attached with a distal end of the lead to an organ inside a human or animal body, wherein the medical implantable lead is formed with an inner lumen extending along essentially the entire length of the lead.
The invention also relates to a method for implanting a medical implantable lead into a human or animal body.
2. Description of the Prior Art
Medical implantable leads are used to connect a device located outside of the body or implanted just beneath the skin at a desired location, with an organ inside the body for monitoring and/or controlling of the organ. Mostly it is an electrical lead, which is adapted to receive and/or transmit electrical signals from and to the organ, respectively, such as for example an electrical lead for connecting a pacemaker or a defibrillator with a heart. However, it could also be some other kind of lead, such as e.g. a catheter for drug delivery or drainage.
The development within this field goes towards thinner leads to save space, e.g. in order to enable positioning of several cardiac monitoring and controlling leads inside the one and same vein. This also has to effect that the leads are becoming less stiff, i.e. more flexible and it is also desirable to have a highly flexible lead to affect the comfort and safety of the patient as little as possible. For example, a cardiac monitoring and controlling lead being too stiff and thin in the outermost distal end portion, could under certain circumstances penetrate into the heart wall and cause severe injuries. However, the thin leads will still have to fulfil all mechanical requirements that the leads will have to withstand during their working life and with thinner and more flexible leads, the risk for fracture of the lead will increase, since the lead may not have the sufficient fatigue resistance that is required to withstand e.g. the movements of a beating heart.
An electrical lead, is normally formed with an inner lumen, which e.g. is defined and surrounded by one or two concentric coils of one or more electrical conducting wires. The lumen is arranged to enable inserting of a guide wire during implantation of the lead, while the one or two wire coils are arranged to define the inner lumen and at the same time give the lead a sufficient stiffness. However, when the cross sectional dimension of the lead, and hence the wire coils, is decreasing, also the stiffness of the lead will decrease.
Recently, a new type of implantable electrical lead has been developed that is compatible with MRI-examination (Magnetic Resonance Imaging), i.e. a person having such an electrical lead implanted, may undergo a MRI-examination without any risk for overheating at the attachment of the distal end to the organ due to induced electric current in the lead. This is accomplished by arranging one or two electrical conductive wire coils in the lead such that sections of the coil are tightly wound, while intermediate sections are loosely wound with longer pitch and increased distance between coils of the wire. It has been discovered that a coil wound in this way will function as a LC-filter, which will suppress certain frequencies, and by carefully adapting the geometry of the lead and especially the length of the tightly and the loosely wound coil sections, respectively, it is possible to suppress or completely block the frequency of the MRI-device. However, the loosely wound sections of the lead will represent a weakened section of the lead which might lead to a subsequent fatigue fracture due to frequent movements inside the body, e.g. from a beating heart.